Smokestack air heater



P 26, 1939. M. B. POWELL 2,174,448

SMOKESTACK AIR HEATER Filed April 28, 1938 Inventor jg Z A itorneys Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to a smoke stack air heater, the general object of the invention being to provide means in a portion of the stack for heating air or other fluid by the products of combustion passing through the stack, so that this heated fluid can be used for various purposes, such as in cotton gins for drying damp or Wet cotton, or for any other purpose where hot air or fluid is used.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts, to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claim.

In describing the invention in detail, reference will be had to the accompanying drawing wherein like characters denote like or corresponding parts throughout the several views, and in which:

Figure 1 is a view in perspective, showing the invention in use on a stack of a furnace or boiler.

Figure 2 is a vertical sectional view through that portion of the stack containing the invention.

Figure 3 is a section on line 33 of Figure 1.

Figure 4 is a view similar to Figure 3, but showing a modification.

In this drawing, the letter A indicates a portion of a furnace or boiler, and the letter B indicates a portion of the stack for leading the products of combustion from the furnace or boiler.

In carrying out the invention, a portion or section of the stack is formed by an enlarged casing l with tapered ends 2 which connect with upper and lower portions of the stack and preferably this casing is located at a lower portion of the stack. Upper and lower flue sheets 3 extend across the ends of the cylindrical part of the casing and a large centrally arranged flue tube t has its ends connected with these sheets,

this tube forming an annular chamber 5 between itself and the casing, the ends of the chamber, of course, being closed by the sheets 3. A plurality of small vertically arranged flue tubes 6 pass through the chamber and have their ends connected with the sheets 3. Of course, the products of combustion will pass through the flue tubes l and 6, and by providing the large central tube 4, the device will not interfere with the draft of the stack. An inlet nipple l is connected to one side of the cylindrical part of the casing and an outlet nipple 8 is connected to the opposite side, these nipples preferably being arranged at the transverse center of the casing. A conduit from a suitable blower device is connected with the inlet 1 and a conduit is connected with the nipple 8 for leading the heated air or fluid to the point of use.

Thus it will be seen that the air or fluid forced into the annular chamber 5 will be heated by the products of combustion passing through the flue tubes 4 and 6, and then this heated air or fluid passes from the nipple 8 into the conduit to the point of use. This fluid is heated by the products of combustion passing through the stack and thus 10 the fluid is heated at no additional cost, but simply by the heat of the products of combustion, which ordinarily goes to waste. By placing the device at the lower portion of the stack, this portion is kept cool and thus has longer life than it would if the device was not used. It is a well known fact that the lower portion of a stack burns out more quickly than other portions, due to the intense heat to which it is subjected.

In the modification shown in Figure 4, a baffle plate 9 extends across the chamber 5, from one end to the other, and is arranged as shown, and the inlet nipple 1 is arranged adjacent this baflle plate so that the fluid must make an almost complete circuit of the chamber before passing from the chamber through the outlet 8'. This arrangement will increase the heat imparted to the fluid by the products of combustion, and by having the inlet arranged with respect to the baffle as shown, the cold air or fluid will not strike the baffle plate directly, which is desirable because the side of the baffle plate next to the outlet will be quite hot, and for the preservation of the baffle plate the cold air should not be driven directly against it, and the inlet should be spaced a short distance from the plate. The arrangement shown in Figure 4 is desirable where the air or fluid must be extremely hot, for instance, where a large amount of cotton is being handled, or the hot fluid has to travel a long distance to the drying room. If the drying room is near the heater, a lesser degree of heat is required. By placing the baflle and the inlet at difierent points in the device, the air or fluid can be heated to the desired degree.

It is thought from the foregoing description that the advantages and novel features of the invention will be readily apparent.

It is to be understood that changes may be made in the construction and in the combination and arrangement of the several parts, provided that such changes fall within the scope of the appended claim.

What I claim is:

Air heating means for a smoke stack comprising a casing forming a portion of the stack, transversely extending flue sheets in the casing, vertically arranged tubes having their ends passing through and connected with the sheets, one of the tubes being centrally arranged and of greater diameter than the other tubes to form an annular chamber between itself and the casing, said other tubes passing through said chamber, a substantially trangentially arranged parti- 1 tion extending across a part of the chamber and 

